SNCA and Parkinson disease: Most activated microglia in PD patient brains are associated with α-synuclein-positive Lewy neurites (Imamura et al., 2003), and there is significant correlation between the expression of M1 activation-associated marker MHC-II and α-synuclein deposition in the substantia nigra of PD patients (Croisier et al., 2005).